1. Technical Field
The present invention relates to a pillow or vertical stand-up pouch having an inside reclose strip constructed using a modified vertical form and fill packaging machine, and the method for making same, that provides for a single piece construction of a reclosable vertical stand-up bag suitable for retail snack food distribution. The invention allows for use of existing film converter and packaging technology to produce a package for moisture sensitive food products or the like with minimal increased costs and minimal modification. The resulting package may be opened, a part of the contents removed and the package resealed to prevent premature deterioration of the quality of the contents because of exposure to moisture.
2. Description of Related Art
Vertical form, fill, and seal packaging machines are commonly used in the snack food industry for forming, filling, and sealing bags of chips and other like products. Such packaging machines take a packaging film from a sheet roll and forms the film into a vertical tube around a product delivery cylinder. The vertical tube is vertically sealed along its length to form a back seal. The machine applies a pair of heat-sealing jaws or facings against the tube to form a transverse seal. This transverse seal acts as the top seal on the bag below and the bottom seal on the package being filled and formed above. The product to be packaged, such as potato chips, is dropped through the product delivery cylinder and formed tube and is held within the tube above the bottom transverse seal. After the package has been filled, the film tube is pushed downward to draw out another package length. A transverse seal is formed above the product, thus sealing it within the film tube and forming a package of product. The package below said transverse seal is separated from the rest of the film tube by cutting across the sealed area.
The packaging film used in such process is typically a composite polymer material produced by a film converter. For example, one prior art composite film used for packaging potato chips and like products is illustrated in FIG. 1, which is a schematic of a cross-section of the film illustrating each individual substantive layer. FIG. 1 shows a sealable inside, or product side, layer 16 which typically comprises metalized oriented polypropylene (“OPP”) or metalized polyethylene terephtalate (“PET”). This is followed by a laminate layer 14, typically a polyethylene extrusion, and an ink or graphics layer 12. The ink layer 12 is typically used for the presentation of graphics that can be viewed through a transparent outside layer 10, which layer 10 is typically OPP or PET.
The prior art film composition shown in FIG. 1 is ideally suited for use on vertical form and fill machines for the packaging of food products. The metalized inside layer 16, which is usually metalized with a thin layer of aluminum, provides excellent barrier properties. The use of OPP or PET for the outside layer 10 and the inside layer 16 further makes it possible to heat seal any surface of the film to any other surface in forming either the transverse seals or back seal of a package.
Typical back seals formed using the film composition shown in FIG. 1 are illustrated in FIGS. 2a and 2b. FIG. 2a is a schematic of a “lap seal” embodiment of a back seal being formed on a tube of film. FIG. 2b illustrates a “fin seal” embodiment of a back seal being formed on a tube of film.
With reference to FIG. 2a, a portion of the inside metalized layer 26 is mated with a portion of the outside layer 20 in the area indicated by the arrows to form a lap seal. The seal in this area is accomplished by applying heat and pressure to the film in such area. The lap seal design shown in FIG. 2a insures that the product to be placed inside the formed package will be protected from the ink layer by the metalized inside layer 26.
The fin seal variation shown in FIG. 2b also provides that the product to be placed in the formed package will be protected from the ink layer by the metalized inside layer 26. Again, the outside layer 20 does not contact any product. In the embodiment shown in FIG. 2b, however, the inside layer 26 is folded over and then sealed on itself in the area indicated by the arrows. Again, this seal is accomplished by the application of heat and pressure to the film in the area illustrated.
Regardless of whether a lap seal or fin seal is used for constructing a standard package using a vertical form, fill, and seal packaging machine, the end result is a package as shown in FIG. 3 with horizontally oriented top and bottom transverse seals 31,33. Such package is referred to in the art as a “vertical flex bag” or “pillow pouch,” and is commonly used for packaging snack foods such as potato chips, tortilla chips, and other various sheeted and extruded products. The back seal discussed with reference to FIGS. 2a and 2b runs vertically along the bag and is typically centered on the back of the package shown in FIG. 3, thus not visible in FIG. 3. Because of the narrow, single edge base on the package shown in FIG. 3 formed by the bottom transverse seal 33, such prior art packages are not particularly stable when standing on one end.
One method and apparatus for making a vertical stand up pouch is disclosed by U.S. Pat. No. 6,722,106, assigned to the same assignee of the present invention and hereby incorporated by reference. One benefit of a vertical stand-up pouch is that it can function as a bowl. Thus, it can be set on a table in the opened position without fear of spilling product. It would be desirable to add a reclosable feature to a vertical stand up pouch.
Many of the reclosable packages disclosed in the prior art utilize a mechanical reclosure means such as interlocking mechanical profiles to fasten the interior package walls together to close the package mouth or an adhesive reclosure means whereby at least a portion of the adhesive is adhered to the outside of the package to close the package mouth. Use of interlocking strips, however, such as zippers or sliders is costly, and complicates the manufacture of packaging. For example, a pair of interlocking strips typically requires that a different interlocking strip, one male and one female, be adhered, by a heat seal or by an adhesive, on opposite inner package walls. Even if the interlocking strips are initially fastened together and initially mated to only one inner package wall, the interlocking strips must eventually be adhered to both opposite inner package walls to function as a reclose strip. If the strips are not fastened prior to adherence to an inner package wall, the strips must then be placed in opposite alignment with one another while on the bagmaker so as to properly function as a reclose mechanism.
Another prior art solution is to use a single sided tape adhered to the outside of a package to close the package. Adhesive adhered to the outside of packages is undesirable because it is difficult to achieve the tight seal desired to keep the contents of an open, rolled-up bag fresh. Further, if the adhesive is strong enough to effect such a bond, it is usually difficult to effect initial release from the outer package wall. Consequently, a need exists for an apparatus and method for making a reclosable pillow pouch in an economical manner that does not use mechanical or interlocking strips and does not require an adhesive on the outside of the package to keep the package closed. Further, use of the reclosable mechanism should be intuitive to a consumer.
U.S. Pat. No. 3,595,468, issued on Jul. 27, 1971, discloses an improved opening device for boil-in-the-bag type packages. The '468 Patent discloses feeding a “heat-sealable strip or tape 34” onto the web face 16 from a supply roll 38. Placement of the strip 34 is below two terminal ends 58 60 of the package extending between two end seals 46 and uses heat and/or pressure to form a seal between the two inner face portions 54 56 of the package. The '468 Patent is not directed towards use in a vertical form, fill and seal machine.
U.S. Pat. No. 3,613,874, issued on Oct. 19, 1971, discloses a reclosable package having a tape heat-sealed between facing members of a flexible pouch adjacent a top edge. Immediately below and parallel to the tape 20 is a tear strip 30. The tear strip 30 extends across the entire front panel of the pillow-pouch type package and around the two side edges and part way across the back panel of the package. Thus, when the tear strip 30 is removed, the front panel above the tear strip is also removed, exposing a pressure sensitive adhesive 7, or tape on the remaining back panel. The back panel having the tape must then be folded over the exterior of the lower portion containing unconsumed product. The '874 Patent requires placement of the adhesive in the transverse direction rather than the machine direction and does not utilize the adhesive to adhere the inner facing package members.
U.S. Pat. No. 4,543,139, issued on Sep. 24, 1985, assigned to Avery International Corporation, discloses a high adhesion or permanent type first pressure sensitive adhesive 11 adjacent a second low adhesion pressure sensitive adhesive 12. The adhesive combination 11 12 can then be placed between a first substrate portion 31 and a second substrate portion 32 to resealably hold the portions 31 32 together. The patent teaches that an end user's action in reopening and redosing the package gradually and progressively mixes the adhesives 11 and 12 to compensate for the adverse effect of contamination on reseal adhesion at the reseal surface 16. The patent is directed towards placement on the outside of a package.
Consequently, a need also exists for a simpler apparatus and method of incorporating an inside reclose strip into a pillow or a vertical stand-up, flat bottom pouch using the vertical form, fill, and seal machine technology. The apparatus and method should allow for ease in size change, and little capital outlay, all while maintaining bag forming speeds typical of vertical form, fill, and seal machine pillow pouch production. Such apparatus and method should ideally produce a pillow pouch or a vertical stand-up pouch having an inside reclose strip, and constructed of material commonly used to form standard vertical flex bags.